One form of typical transformer includes a squared figure eight core consisting of ferrous laminates with coils encircling the center cross bar of the core. Conventionally, laminations of the core, possibly including a cover which provides mounting feet, is secured together by fasteners (bolts, screws, rivets) which pass through clearance holes punched in the corners of the core laminations. The holes themselves reduce the magnetic flux paths which in turn causes increased core losses and requires increased excitation current. Furthermore, any metallic fasteners passing through the core must be provided with sleeves or spacers so as to insulate the fasteners from the core laminations, thereby to avoid electrical shorting of the laminations.
The use of such fastening devices generally involves a lengthy assembly time. In addition, excessive torque or pressure applied to the fasteners during the assembly process may draw laminations together too tightly and result in a breakdown of any insulative coating on the laminations. This results in the generation of eddy currents and commensurate further losses.
Conventional core clamp designs do not cover the entire core, which may leave sharp corners of the laminations exposed, making the transformers difficult to handle. Typically, the portion of the core not covered by the clamp is treated with varnish or paint to both inhibit and hide rusting of core laminations. However, the paint or varnish applied to the core or the clamp makes it difficult to establish a reliable electrical ground through the entire assembly.
The foregoing considerations apply also to similar cored coil electrical assemblies, such as inductors.
One purpose of the present invention is to provide a core clamp which facilitates quick assembly. Another purpose of the invention is to provide a core clamp which avoids the need for fasteners extending through the core laminations. A purpose of the invention is to provide a cored coil clamp which does not require excessive compression of the core laminations during assembly A further purpose of the invention is to provide a cored coil clamp which covers all of the exposed surfaces and corners of the core laminations.